Fair Value Measurements (Details 2) (Level 3, USD $) In Millions, unless otherwise specified																						3 Months Ended
	Mar. 31, 2014 FTRs	Dec. 31, 2013 FTRs	Dec. 31, 2012 FTRs	Mar. 31, 2014 FTRs FES	Dec. 31, 2013 FTRs FES	Dec. 31, 2012 FTRs FES	Mar. 31, 2014 Non Utility Generation Contract		Dec. 31, 2013 Non Utility Generation Contract		Dec. 31, 2012 Non Utility Generation Contract		Mar. 31, 2014 LCAPP Contracts		Dec. 31, 2013 LCAPP Contracts		Dec. 31, 2012 LCAPP Contracts		Mar. 31, 2014 Model FTRs	Mar. 31, 2014 Model FTRs FES	Mar. 31, 2014 Model Non Utility Generation Contract	Mar. 31, 2014 Model Minimum FTRs	Mar. 31, 2014 Model Minimum FTRs FES	Mar. 31, 2014 Model Minimum Non Utility Generation Contract MWh	Mar. 31, 2014 Model Maximum FTRs	Mar. 31, 2014 Model Maximum FTRs FES	Mar. 31, 2014 Model Maximum Non Utility Generation Contract MWh	Mar. 31, 2014 Model Weighted Average FTRs	Mar. 31, 2014 Model Weighted Average FTRs FES	Mar. 31, 2014 Model Weighted Average Non Utility Generation Contract MWh
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value	$ (1)	$ (8)	$ (1)	$ (4)	$ (8)	$ 0	$ (185)	[1]	$ (202)	[1]	$ (254)	[1]	$ 0	[1]	$ 0	[1]	$ (144)	[1]	$ (1)	$ (4)	$ (185)
Fair Value Inputs, RTO Auction Clearing Prices																						(4.20)	(4.20)		7.60	7.60		0.80	0.60
Fair Value Inputs, Power																								600			5,422,000			1,033,000
Fair Value Inputs, Power, Regional Prices																								47.90			59.00			53.50

[1] Changes in the fair value of NUG and LCAPP contracts are generally subject to regulatory accounting treatment and do not impact earnings.